This branch includes a benchmark to test the optimization of the htmlspecialchars function. The previous version is still available as htmlspecialchars_old. The benchmark code is in benchmark.php.
Just build PHP with mbstring and run:
./sapi/cli/php benchmark.php----------------------------------------------------------------------------------------
| Test | old avg(ns) | new avg(ns) | diff(%) |
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| Empty string | 63 | 42 | 50.00% |
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| 1 char | 64 | 78 | -17.95% |
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| 4 char | 76 | 81 | -6.17% |
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| 8 char | 93 | 86 | 8.14% |
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| 1000 spec. char | 14257 | 8449 | 68.74% |
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| ASCII letters | 9647 | 3293 | 192.95% |
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| Emoji UTF8 | 19212 | 14991 | 28.16% |
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| Cyrillic UTF8 | 17028 | 11767 | 44.71% |
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| Chinese UTF8 | 18220 | 14904 | 22.25% |
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| Japan UTF8 | 18223 | 14880 | 22.47% |
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| Cyrillic CP1251 | 9664 | 3858 | 150.49% |
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| Chinese Big5 | 27433 | 24126 | 13.71% |
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| Japan SJIS | 16125 | 16090 | 0.22% |
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| 200 entities !double_decode | 12979 | 7499 | 73.08% |
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| 800 entities !double_decode | 10363 | 9454 | 9.61% |
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The main performance improvement comes from fast-path handling of ASCII bytes and single-byte encodings using a lookup table for special character detection.
The new validate_utf8_char function efficiently handles multi-byte UTF-8 characters.
Overall, the logic for character processing and validation has been improved.
Performance is lower for single-character strings due to the overhead of initializing the LUT.
In the benchmark, I tried to cover a variety of scenarios with different encodings and flags, but feel free to run it on your own data and share the results.